The workshop on Experimental Models from the Bursa of Fabricius will be held October 4-6, 2002, in the modern conference facilities of a leading biomedical research institute, the Fred Hutchinson Cancer Research Center, in Seattle, Washington. Experimental model systems based on the bursa and its derivatives provide highly productive opportunities for study of biological problems of broad significance. Examples include: (1) pathogenesis of neoplasia induced by oncogenes such as c-myc, c-myb and Rel, including analysis of angiogenesis and programmed cell death. (2) B-cell development, including mechanisms of immunoglobulin gene diversification, (3) somatic stem cell biology and transplantation, (4) targeted gene deletion and replacement in cultured bursal-derived (DT40) cells. This latter technology, unique for use with cultured vertebrate cell lines, has been exploited for novel and revealing experiments in an increasing range of applications including; recombination and conversion in lg gene diversification, signal transduction pathways from B-cell receptors, regulation of RNA splicing, function of centromeric proteins in chromosome dynamics and targeted mutagenesis in human chromosomes shuttled in and out of DT40 cells. Despite such achievements these experimental approaches are not as widely known and applied as might be expected from the opportunity they represent. One limitation has been a lack of chicken genomic resources for both construction and analysis of experiments in the bursa and DT40 cells. Therefore, the workshop will feature (5) the expanded array of genomic resources now available and/or under development for use in these systems. The workshop will bring together, for the first time, leading investigators working with these related experimental systems in order to meet each other and share their findings and expertise. A core of 17 leading investigators are invited speakers. The remaining program of speakers and posters will be selected from submitted abstracts in response to a general announcement. The meeting will be open to interested students post-doctoral trainees and scientists up to the capacity of the facilities. This workshop will serve to stimulate further development and application, and to educate interested young scientists to the opportunities presented.